car is eating rear ball joints

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Sr. Member

I have this issue with my 2000 Eldorado rear suspension, nobody I've talked with can even guess what the issue might be. I hope someone here can give me some kind of feedback, because I'm at a total loss.

These cars had issues with the rear suspension ball joints wearing out about 50k-75k miles, that's a known. It has a knuckle with a lower and upper axial ball joint. The upper is about half the size of the lower. When they wear out, you get a noise like a bowling ball rolling around in the trunk. Mine had this at 55k miles on the OE parts. GM never sold the bushings alone, just the complete knuckle assembly ($500). But the aftermarket has replacement bushings for $25 each.

I replaced all 4 at once. Used Moog parts, and they have this bulletin on the parts: http://www.moogproblemsolver.com/_pdf_En/MOOG_PS_Bulletin_210006_K200174_K200175_En.pdf

Anyway, about a year after I noticed that the noise had come back from the right rear. I found the upper joint had worn out again, it had a noticeable looseness. I called the supplier, the Moog is lifetime warranty so they sent a replacement. Pressed it the new one in, was silent for 500 miles. Then the rumbling started all over again. Same ball joint. Figured this was a defective part, the company sent another. I replaced this, and here were are 500 miles later it's rumbling again. This is beyond belief... something is definitely wrong for the same one ball joint to keep failing.

I just can't imagine what would cause one ball joint in a suspension to wear out. I've checked everything, nothing is out of place or binding or loose. I pressed all 4 of these parts in the same exact way. I had the alignment checked, the rear is perfectly in spec. I just don't understand this. What else would wear out a ball joint of this type except lack of lubrication?

The only thing--and I'm grasping at straws here--is *maybe* that one knuckle bore is a tighter tolerance than the others. Maybe when I press it in it's distorting the metal slightly, and causing premature wear of the joint? That's the only thing I can even guess is wrong. Maybe I could try getting a junkyard knuckle and putting in 2 new bushings, but I'd have to get a new bearing capsule. Or I could try installing a new bushing by heating up the knuckle with a torch instead of pressing it cold? I'm at a loss.

Is it even remotely possible the noise is from the bearing, and maybe the new ball joint hides the noise for a short time? I do not think it is, but as I said, I'm grabbing at straws here. I don't feel any play in the bearing.

Thank to anyone who had read this whole story, and I appreciate any suggestions.
-Michael

wrench

LOL, can't say the guys at ackits didn't warn you that you are going to have constant problems with this car. Was at my dealers a couple of months ago looking for my stepdaughter. He said he has a nice 2001 Caddy for her. Said I came here to relieve myself of car problems, not buy more.

He said he could sell me a maintenance insurance policy. Said I already read all the small print, one of the exclusions is, whatever problem you are having with your vehicle, not covered by this policy. Only the components you are not have problems with are covered.

Sr. Member

Bill, there's a thought, but the shock is new (Delco). I wondered about the tire myself, because they are a few years old but with plenty of tread. But the car rides like a Cadillac should, no vibration. And also, say the tire was out of balance, should that be enough to wear out a ball joint in 500 miles? That seems a bit excessive to me.

Danica, these are axial ball joints, no taper or threads. Pressing was done on the outer collar. The seal is fine, considering it's brand new. However, on the 3 other ball joints that are nearing 2 years old, the seals are showing signs of cracking. There's top shelf parts for you...

Haha, well Nick, I don't think their prediction was that dire (or maybe my memory is hazy lol). This car has been nearly trouble free, except for this one sticking point. And the worst thing is I know exactly *what* the problem is, I just can't seem to fix it

wrench

Not even sure as to what it does, but is called a pivot bushing. Appears to be a lack of lubrication problem.

Sounds like Moog should be addressing this problem. And lack of lubrication is appearing to be a major problem, always install zerk fittings on conventional ball joints so I can squirt some grease in there every couple of years. Sealed ball bearings are really a major problem, where in the hell is the grease. And what nitwit decided to make the cages out of plastic. Those go back, only proper way is riveted steel cages, spot welded ones are equally crap, but not nearly as bad as plastic.

Have over 50K on my upper strut bearings without problem, originals were never greased from day one. And neither were the new replacements, packed those full with Wolf's Red bearing grease.

Appears according to Moog, you have a very common problem, but did they really find a solution for it? I no longer have access to a Rockwell hardness test, maybe these things are made out of pot metal.

Sr. Member

Nick, yes that is the part. That page is what I linked to in my original post.

I agree with you, a lack of lubrication would be the only thing that would wear out a ball joint like that so quickly. I can't think of anything else. But, I also didn't open up a brand new part to check if they lubricated it. It had lots of grease on the outside, maybe that was it and none got inside the boots. I don't know. But at the same time, this is 3 separate parts I got that all failed in the same timeframe in the same location. Something seems to be wrong with that particular part in that location.

The picture in that Moog page is not very good. Here is what we're talking about:

And there are no instructions with the Moog parts that say how I should be installing them, so I just pressed them in cold (all 4 done the same). The factory manual does not cover replacing the bushings alone, because GM only sells the complete assembly.

I guess I could go to a junkyard and get another knuckle, press in 2 new ball joints and get a new bearing capsule, but that's $120+ for something that should not be an issue with new parts. Or I could go buy a Dorman knuckle bushing, maybe they actually have grease inside the parts. But Moog is supposed to be the best. And I'll bet all these parts are made by Federal Mogul anyway.

wrench

Looks like a bushing for the upper and lower control arms. Shouldn't have any lateral movement, strictly up and down. I gather that through bolt locks that balled center piece in that end bushing to prevent lateral movement and is the friction of up and down movement wearing out that ball. What about torquing that through bolt, could that be crimping that ball and bushing? Would certainly need a lot of grease in there.

My 92 DeVille only has a single lower control arm with a real ball joint in it. Uses a coil spring with an external strut that is real easy to change. Has been trouble free, maybe that is why they got away from that design so you are sure to trade-in before your warranty expires.

But this can go on and on, can make a engine driven diesel fuel pump capable of producing 1,500 psi, certainly could have modified an engine driven conventional fuel pump to get a mere 35 psi with a two buck repair kit. Instead of that way overprice piece of crap they bury inside of the a fuel tank. Or even have the luxury of being able to open a car door after an ice rain. The problems we run into day are unreal, and more important, completely unnecessary.

Only solution I see is to leave these things in the showroom where they were designed for.

Sr. Member

Yes, that's exactly how they work. No lateral movement, the knuckle is held with a fixed tie rod. I torqued the bolts to what the FSM says... something like 50 ft.lbs top, and 75 ft.lbs. bottom. As I've said, none of the other 3 joints have been any trouble after 20k miles and nearly 2 years. It's just that one. It makes no sense to me at all.

I'm just not sure what to do next. Try another brand of ball joint or what...

wrench

Am I correct in thinking that this 'ball joint' looks like a control arm bushing, but is different because the inner sleeve is not bonded to the rubber part of the joint? Replacement instructions do not include the caution "Tighten through bolts with suspension at normal ride height" or similar instruction.

Sr. Member

There actually is a "ball" inside that piece, but it only allows movement up and down, not side to side (hence "axial" ball joint). The rubber ends are actually just dust caps to keep the grease inside the joint.

Yes, the knuckle is torqued with the suspension at ride level, which I did. The only thing that would happen if I installed them with the suspension at full travel would be that the boot would tear when it hit the top bump stop. But I did it it by the book.... many times.... getting tired of replacing these parts, for sure.

wrench

Bit mystified by the construction of this joint. Only has one bushing, even if the inside of it was spherical, would only support half the ball. What supports the unbushed side? From appearance in that Moog photo, the wear is on the outer periphery of the ball, only making a point contact unlike a ball joint that is making contact on at least 75% of the ball.

Seems like a split bushing with two spherical sides are in order for an improvement. No doubt what both you and Moog say, this joint is a problem. See they started with the 94 DeVille when they already had a reliable joint. Just like when the engineers went to work, what should we screw up today?

Had equally frustrating problems with my 78 Fleetwood, major over steering problems could not resolve with a way too heavy of an engine in that reduced body, and rear disk brake problems neither my dealer or Cadillac could resolve. Solved that problem by getting rid of it. Could have switched to drum brakes on the rear, but really no good cure for that over steering problem.

wrench

I've been wondering if the 'ball' had worn away the rubber is any particular direction. That might be a clue. I also question the hardness of the rubber...hard and soft rubber looks just the same, and if Moog chose a soft compound that wears prematurely (but gives a great ride until it loosens up) it may be time for another brand.

Sr. Member

Bill, unfortunately I don't have any of the worn out parts--I had to send them back for the warranty replacement. I never opened them up, just send them right back. But it's very easy to describe how they failed... first was the rumbling in the rear end, which gradually got louder. Then they wear out to the point where the center section of the ball joint is loose in the outer. You can grab the top of the tire and pull in and out, hear the clunk and feel the play. It feels like a severely loose bearing, but only in the top-bottom direction. When I take the old ball joint out, I can feel and see play between the inner and outer section holding it in my hand.

Nick, I see exactly what you're saying. I don't know how the ball joint is supported internally. It certainly looks like it has a point contact. I think that maybe the ball is encased in rubber and that is just the end-result of the rubber wearing out. But I can't tell you for sure.

Danica, I really don't know what to think. Again, I keep coming back to the fact that it's just the ONE part that keeps failing. I can not fathom what could be different about that right rear top ball joint that it wears out in a few hundred miles. I could buy another brand, I think Dorman and maybe Raybestos make the same parts. The guy at Rockauto even told me he can't understand why the Moogs would be a problem, they're supposed to be the best (lifetime warranty).